Smoothed particle hydrodynamics (SPH) is a computational, mesh-free, method used for simulating the dynamics of fluid flows. In particular SPH has proved particularly useful in astrophysical simulations such as star and galaxy formation, for example the massive millennium simulation [1] probing cosmic structure formation:

For more information about SPH and its implementation I recommend a recent review by Volker Springel, which I found very clear and informative as a newcomer to the field.

One of the major issues at present how to incorporate the evolution of the magnetic field, and it's subsequent effect on the dynamics, in such simulations. Recent publications concerning the issue of magnetic fields in SPH are [2] and [3]

I am currently visiting the Institut für Theoretische Astrophysik at Heidelberg University to visit the star formation group and work on a technique to resolve this issue.
The idea involves modeling magnetic fields as thin flux loops, automatically satisfying a divergence free field. This is based on work I have published on a flux rope approach to numerical dynamo simulations, see my publications page for more details.

Some earlier results are presented here, this initial simulation shows an expanding pocket of gas and this influence on an initially uniform magnetic field in the z direction.
Note this is a purely kinematic simulation, hence the expanding gas feels no back reaction from the magnetic field.
To view the animation please click on the image below. The left panel shows the SPH particles colour coded according to local density, the right panel shows the magnetic field with flux tubes colour coded by the log (base 2) of the magnetic field strength.


In this second simulation shows we include self-gravity causing the cloud to collapse;
again this is a purely kinematic simulation.
To view the animation please click on the image below, colour coding is as above.

1. Simulations of the formation, evolution and clustering of galaxies and quasars, Springel et al., Nature, 435, 7042, 629-636 (2005)
2. Magnetic field evolution in simulations with Euler potentials, Brandenberg, A., MNRAS, 401, 1, 347–354 (2010)
3. Smoothed Particle Magnetohydrodynamics – IV. Using the vector potential, Price, D.J, MNRAS, 401, 3, 1475–1499 (2010)
Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License